The present invention relates to a bumper crossbeam as component of a bumper of a motor vehicle.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Motor vehicles have bumpers which are arranged in the front and rear zones of the vehicle. Load-Bearing component is a crossbeam which is connected on both its end zones via crash boxes with the side rails of the vehicle. Plastic casings can be provided to cover the crossbeam to the outside and are intended i.a. to match the optics of the vehicle design. The bumper transfers the impact energy generated at crashes at slight speed via the crossbeam to the crash boxes which convert the kinetic energy into plastic deformation so as to dampen the impact and to reduce stress on the remaining vehicle structure and vehicle occupants. For ecological and economic reasons, use of material and production costs for the crossbeam should be kept to a minimum while still affording good crash characteristics.
To date, it has been proposed to establish individual section zones of the crossbeam of varying material thicknesses and strength to meet requirements at hand. This requires various rolling and winding processes of the starting material and complex combination of joining and shaping working operations. In particular, when methods are involved which include different joining processes for producing varying material thicknesses in the run-up to the shaping operation, problems have been encountered in connection with dimensional precision of the end product. While roll-forming has been considered an efficient manufacturing process to attain high shaping speeds, small number of operating cycles, and high dimensional precision, roll-forming suffers shortcomings relating to a small material thickness throughout which can be adjusted only by doubling the material.
It would therefore be desirable and advantageous to address prior art shortcomings and to provide an improved bumper crossbeam which is easy to manufacture and lightweight while still maintaining strength and being reliable in operation.